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Molecular Systematics and Biogeographical History of Pitvipers as Determined by Mitochondrial Ribosomal DNA Sequences
Christopher L. Parkinson
Vol. 1999, No. 3 (Aug. 2, 1999), pp. 576-586
Stable URL: http://www.jstor.org/stable/1447591
Page Count: 11
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Systematics of the snake subfamily Crotalinae (Serpentes: Viperidae) were investigated by means of mtDNA (12S and 16S rDNA sequences); 45 species, which included all genera, were sequenced and analyzed using both maximum parsimony (MP) and maximum likelihood (ML) as the optimality criteria. Differential a priori weighting methods were employed, because there was a transition bias within the data. All analyses support Azemiops feae as the sister to a monophyletic Crotalinae. The New World pitvipers are monophyletic, but the identification of their sister group is unclear. These data suggest a single invasion into North America, a subsequent north temperate and tropical divergence, and at least three invasions of South America. All currently proposed Central American genera (excluding Crotalus) are valid. Crotalus is paraphyletic with regard to Sistrurus, and Bothrops is paraphyletic with respect to Bothriopsis. Inclusion of Porthidium melanurum in Ophryacus is supported. The Old World Protobothrops is monophyletic and perhaps the most basal crotaline. This, along with New World monophyly, suggests that pitvipers evolved in Eurasia. All proposed Old World genera are monophyletic; thus, 19 genera are currently recognized within the Crotalinae.